NASA probes Mars orbiter for fuel disappearance.

NASA and Lockheed Martin Space engineers have investigated the fuel supply of the Mars Odyssey orbiter, which has been in space for 22 years, without the use of a fuel gauge. The probe was estimated to be close to running on empty, but the investigation revealed that the missing fuel was never missing at all. The engineers discovered that heaters along an Odyssey fuel line were warming connected propellant tanks, making them appear emptier than they actually are. The team now understands the craft better than they did previously and Odyssey has enough fuel left to last a few more years at least.